>> Actually The neutron has mass slightly larger than that of a proton: >> 939.565378 MeV compared to 938.272046 MeV. Consequently, a deuteron has >> slightly more mass than a diproton.
>> That is one of the many reasons why the reaction on the Sun, the one that >> results in a deuteron is extraordinarily rare. It is basically endothermic. Jones You are considering the combined mass of two isolated protons. However, the mass of a diproton is greater than this and it is greater than the mass of one deuteron. Harry The energy necessary to make up the mass difference between two protons and the deuteron - which occasionally derives from their endothermic fusion (in the solar proton chain reaction sequence) is supplied by either the momentum of the protons or by absorbed gamma radiation - which is intense in the solar core. What you are saying essentially is that proton momentum can add mass to the diproton - and that is the same thing. A diproton has too short a lifetime to accurately measure its mass, but we can assume that it gains mass from the collision energy - and that is the missing mass-energy which is necessary to balance the equation.
